Effect of panretinal photocoagulation on macular vasculature using optical coherence tomography angiography

Background: To evaluate the changes of macular vascular density in the superficial capillary (SCP) and the deep capillary plexus (DCP), foveal avascular area (FAZ), choroidal flow, and macular thickness after pan-retinal photocoagulation (PRP). Methods: In this prospective interventional non-comparative case series, patients with very severe nonproliferative (NPDR) and early proliferative diabetic retinopathy (PDR) and no significant macular edema who were candidates for pan-retinal photocoagulation underwent measurement of corrected distance visual acuity (CDVA), optical coherence tomography (OCT), Optical coherence tomography angiography (OCTA) at the baseline, 1, and 6 months following completion of PRP treatment. Results: Thirty-nine eyes from 21 patients with diabetes were enrolled. Superficial and deep capillary plexus densities in the foveal and parafoveal area didn't change significantly 1 and 6 months post-PRP (p > 0.1 in all of them). The FAZ area constricted 6 months following PRP (p = 0.075). Based on the calculated circularity index, the FAZ became significantly more circular after 6 months of follow-up (p = 0.047). Although the choroidal flow area increased after PRP this increase wasn't statically significant neither at 1 month nor at 6 months post-PRP (p = 0.31 and 0.23, respectively). Conclusion: Although OCTA parameters were not significantly affected by PRP at both short-term (1 month) and long-term (6 months) follow-ups, the FAZ area became significantly circular after PRP may be due to redistribution of blood flow in hypoperfused foveal capillary plexus.